NOAA scientists explore the Arctic during a 2005 mission.

Climate scientists have projected the North Pole will lose its summer ice cap after 2050 due to a warming climate melting sea ice. But a new study in the Geophysical Research Letters journal, led by James Overland of the National Oceanic and Atmospheric Administration, used three methods of projecting future ice cover and predicts summers with no ice much sooner.

“(A)ll three suggest nearly sea ice-free summers in the Arctic before the middle of this century,” says study co-author Muyin Wang of NOAA’s Joint Institute for the Study of Atmosphere and Ocean, in a statement.

The estimates produce ranges for an ice-free Arctic from 2020 to after 2040. “This paper should not be used as an argument against further modeling, but quite the opposite,” says the study. “It is reasonable to conclude Arctic sea ice loss is very likely to occur in the first rather than the second half of the 21st Century, with a possibility of loss within a decade or two.”

The amount of Arctic sea ice increases each winter and decreases in summer. It reached its maximum winter amount in March, about 5.81 million square miles, according to the National Snow & Ice Data Center. That was well below the average seen in previous decades.

Simply extending summertime ice melting trends into the future in a straight line predicts an ice-free summertime Arctic by 2020, the study shows. Adding a few random ups and downs to current melting trends pushes it back to 2030, while a more complicated model suggest an ice-free Arctic won’t appear until after 2040, most likely around the year 2060. But none of the methods see the polar ice cap remaining intact in the long run, Wang notes.

Disappearance of the summertime ice sheet will lead to cascading effects throughout the Arctic food chain, for everything from plankton to fish to polar bears and other creatures living there. Geopolitical jousting over navigation and mining rights have already started, amid concerns about landslides due to melting permafrost and other land effects.